U.S. Pat. No. 5,365,214 discloses a musical wireless alerting system. It includes several detectors which transmit radio-frequency (RF) signals to a common receiver. The detectors include manual switches thereon to allow manual selection of a song or melody. The selection is coded in the form of an audio code which is transmitted to the receiver. The receiver detects any RF transmissions and verifies that the received transmissions are identifiable with the receiver. Upon verification, the receiver reads the audio code and compares same to a plurality of stored songs or tunes within memory for transmission to a speaker which plays the song or tune. Each of the detectors may sense different predefined conditions and indicate different audible indications to be played. The detectors may sense conditions such as opening of the door or depression of a doorbell.
Prior art teaches a general short-range remote control device which comprises an encoder or a transmitter with an encoder (herein called encoder device) and a decoder or a receiver with a decoder (herein called the decoder device). The encoder device is mainly designed to provide a common house code and unique data codes to allow the decoder device to respond and function accordingly. The house code is normally achieved by a dual in-line package (DIP) switch with eight positions to provide 256 different combinations. For recognition, both the encoder and the decoder devices should match their house code, or else the decoder device would not be able to respond to the command of the encoder device.
As mentioned above, since the existing prior art can only provide limited number of house codes to choose from, it is difficult to avoid interference from consumer's neighbors who are also using the invention. It could be troublesome to change the house code, because the consumer would not know the codes of their neighbors. Changes need to be made on all encoder and decoder devices. Furthermore, an intruder with the same product can easily interfere this remote control device by changing the house code one by one and it will trouble and inconvenient the consumer(s).
The invention introduces a new concept to provide one unique identification (ID) code for each encoder device which is pre-set or built-in during manufacturing. Through an automatic or manual learning process, the receiver can memorize many ID codes in the electrically erasable programmable read-only memory (EEPROM) integrated circuits (IC) or flash read-only memory (ROM). Once memorized, the contents inside these memory devices will not be lost or changed, even if there is power supply interruption. The receiver will be free from interference from a different transmitter, since its ID code does not match and will not be recognized.
This new concept teaches a separate unique ID code for each encoder device. There must be a wide choice of ID codes for hundreds of thousands of encoder devices, in order to avoid interference. This is supported by applying a four quadric or higher communication protocol coding arrangement. The arrangement allows for increased transmission power as regulated by Federal Communications Commission (FCC) due to low average on period per duty cycle.